question_answer

A particle is kept at rest at the top of a sphere of diameter 42 m. When disturbed slightly, it slides down. At what height h from the bottom, the particle will leave the sphere:

A)  14 m  

B)                                         28 m                    

C)  35 m                    

D)         7 m

Correct Answer: C

Solution :

The condition of slipping by particle from top is given by \[\cos \theta =2\text{/}3\] From the figure, \[h=r\cos \theta \]    \[=21\times \frac{2}{3}=14\,m\] Therefore, the required height at which the particle will leave the sphere is \[=21+h=21+14=35\,m\]